Neda Agha Soltan, the young Iranian woman whose face became the international symbol of protest against Mahmoud Ahmadinejad, told her fiancé she was prepared to "take a bullet in the heart" in the fight against the president's regime.

The revelation comes as her boyfriend speaks out for the first time after being imprisoned following Neda's death last June, when she was shot by Iranian police at a demonstration in Tehran. Caspian Makan, a photographer, spent two months in prison for criticising the authorities after her death. In a moving interview, he told the Observer that far from being a bystander caught up in the demonstrations, she was committed to the overthrow of Ahmadinejad. As a result of her high-profile presence at the protests, he believes she was targeted by the regime loyalists who killed her.

Makan has fled Iran and given two in-depth interviews. His meeting with director Angus Macqueen, which is featured in today's Observer Review, will appear in a BBC film about Neda. In both interviews she emerges as a markedly different figure to the young woman depicted at the time of her death. Her fiancé describes her as politically active and assertive, convinced she was fighting for "democracy and freedom" for Iranians. Neda joined the first wave of protests. After the election results were announced, she headed to the Interior Ministry in central Tehran – a focal point for the emerging movement supporting Ahamdinejad's election rival, Mir Hossein Mousavi. Makan remembers telling her that the scenes she described to him would quickly lead to a violent response from the regime.

She said: "No, they will continue because the people are too many and the scale too widespread… Everyone is responsible for reaching democracy," Makan recalls her as saying. "If I get shot in the heart or arrested, it's not important because we are all responsible for our future."

Although he was nervous about Neda going to the demonstrations, Makan said she insisted on participating. The last time he spoke to her, they had an argument over whether she should continue attending, as the violence increased.

Neda refused to listen to her boyfriend's pleas and criticised him for not documenting the street scenes. "Neda was present at the front line of the protests from the very first day," said Makan. "She was a natural leader and attracted many [protesters] to her side. I think that is why she was shot. The Iranian state and its security officials did not want her, they wanted to extinguish her."

Makan also reveals that Neda had no sympathy for either of the main opposition candidates who were challenging Ahmadinejad's claim of victory in the election.

Makan was unaware that Neda had been killed until the morning after the shooting had broken out. It was only then that Makan watched online the video of Neda's death in a Tehran street that would become the symbol of the crushing of the protests.

His public criticism of Supreme Leader Ali Khamenei in an interview led to the inevitable. Three days later, he was arrested, according to his interrogators at Evin prison, "on the personal order of Khamenei".

Finally released after 65 days, he was asked to sign an undertaking never to speak about Neda's death again and never to leave the country.

Pretending to depart on a photography trip, Makan headed north, but then drove for two days to one of the country's borders where he had arranged to meet a people smuggler. His escape ended in an eight-hour hike through the mountains.

Neda Agha Soltan, killed on camera by a sniper's bullet, became the symbol of opposition to President Ahmadinejad in Iran this summer. Her boyfriend, Caspian Makan, who has just fled the country, talks to Arash Sahami and Angus Macqueen about their romance, his imprisonment after her death and his terrifying escape